Conical mill.



H. W. HARDINGE.

CONICAL MILL. APPLICATION FILED JUNE 29. 1917.

Patented De0.24,19 18.

follo in working with capacities DINGE, or new YORK, n". Y.,

Miss or NEW YDBK,

isms

s, a Ll.

ASSIGNGR cement MILL.

apgilieation filed June as, 151?. Serial no.

'1 0 all 41 ham was concern Be it known that 1, Hanna \V. HAnoINon, a citizen of the E iited States, residing at New York count; and State of New York, have in' prove u certain new and useful Im- Conieal Mills, of which the toll, clear, and exact description.

The inten on which constitutes the subject matter 01' t1... ication relates to an ii roaemei t T l mil l er consisting, in its most common form, of cones arranged case cylindrical section between the two) and having an inlet opening at the apex of one cone. and an outlet opening, at the apex of with a mill of this type that Figure 1 illustrates a longitudinal section of a conical mill.

Fig. 2 is a section Fig. l.

The distinguishing structural characteris tic OI" all conical mills is the tapering shape of the portion which may be conveniently referred to as the outlet portion) next to the axial outlet opening. This tapering form causes the material in the outlet portion to assume a sort of vertical stratification accordingto size, the largest pieces being at the plane of greatest diameter and the pieces diminishing in size toward the outlet, as fully described in my Patent No. 908,861.

In most cases the asserting of the material tapered according to size, produced by the form of the outlet portion, permits only parthe desired degree oi fineness to 1sticles of sue from the outlet under normal load, but above normal, as

is often desirable to increase capacity of taken on line 2-2 of a single mill, it is found that some oi": the ma terial discharge-cl is composed of particles which are too large for the purpose desired. in such cases it is necessary to separate the coarse uncrushed material and return it to the f l, or to another mill, for regrinding. Lee present invention relates to this probl i, and its object is to provide means who; shy the desired separation will he effects particles election,

tained in the mill for further rel the case without the screen. Hence it is economically desirable to PIOYlQiG Jill purpose which shall be simple Specification of Letters lfatent.

lo base (preferably with athe cone,

inside of the mill and the coarse L tead of p rmitting them to pass,

in character and effective in operation, and

which can be easy." and chea )l a'oolied.

a In 0 eratlno' conical nulls I01 :1 nimiberof '1" 1 .4. years .1 have ooserved theu the diameters and consequent dlfIGI'GIlCG in peripheral speeds at dill rent portions of the cones has the distinctive feature of drawing or massing the contents (when in operation) toward the greatest diameter. This result ensues to an extent that when the mill is filled to its center with grinders and mate'- rial being ground, the inlet and out-let trunnions are practically closed to the admission of more material, yet when the mill is rotated the above mentioned material tends to draw away from the mill, piling up at its greatest diameter, leaving more or'less free spaces below the axis, as shown at a. This free space due to segregating of material does not occur in a cylindrical mill in which the peripheral speed is the same throughout its whole length, except perhaps whenthe' mill is fed below the desired maximum capacity, at which time, of course, the necessity for any screen does not exist.

I also take advantage of the fact that zall sticn.

tain as great a quantity of large unground' material or gr nding mediums against its surfacelowing to the classifying action of hence the screen area for equal volumes of material passing through the mill is less than its averagediameter and more nearly adjusted to exact requirements.

Referring specificall to the reference numeral 1O designates the inlet portion of a conical mill, 11 the outlet poo ti-on, andIQ't-he cylindrical portion between the conical portions. The mill is also provided, among other things, with the trunnions 13 at the apex: of the cone 1t and 14. the apex'of the cone 11. Any suitable bearings and. maysbeprovided so. as

the conesto the center of :lGSSCl and practihe screenin a cone is not required to redifference in drawing,

to enable it to rotate about its longitudinal axis,t and any suitable mechanism may be employed to effect said rotation, such as the gear indicated. A convenient and effective means for preventing large pieces orbits of.

material from escaping along with material of the desired degree of fineness is illustrated at 17 and comprises a screen inside the conical outlet portion of the mill. A

screen located in the cone of a grinding mill has the advantage of a comparatively imobstructed area ofthe screen and obviates the excessive grinding area on the screen by the balls and grinding mediums. The 'objeetof this screen is to retain within the mill the material being ground'until it is of a size which will pass through the meshes or orifiees ofthe screen. This screen or barrier may be provided with a central orifice or opening 18 of'suiiicient size to pass 'material substantiallyo'r approximately as large as that originallyfed to-the mill, this openj ing acting as a safety or overflow opening ,to prevent chokingfof the mill with the 25 material undergoing disintegration. The

exacttlocationfof the screen within the conical portion 11 for bestresults is dependent upon the size and character of the matcriah' being ground; -If tlie n ia .te1ial being gioiind is c0arse.:,then ;the screen should be placed more or less adjacent'to the base of theco'nif calportion. If, however, the material be- 'ing ground is not so coarse the screen should beL-arranged nearerthe apex of the cone. For ordinary requirements the screenis preferably located midway between the apex and base of the cone.

The material after passing the screen may be removed byany Well lgnown means, pref ;erably by the lifting vanes 19. "This keeps the. material removed on the outletside so as to insure free "passage of the finer material J through the -screcn.',1 It will-therefore be seen that the screen back of the out-let defines two chambers, one for the unscreene'd and the other for the screened material.

What I claim is 1. The combination with a grinding mill of the kind described having a conical out- .let portion, of a screen secured to the walls of said, conical portion of the body of said mill within the same and back of the outlet thereby forming a chamber therein on each side of said screen, one of which is adapted to receive;the screened materiahand means for removing the material after passing the screen so" as to provide a hydrostatic or gravity he'ad on the free side of the screen wherebya free How of the material through.

the screen is provided.

2. The combination with a grinding mill of the class described having an inlet opening and a conical outlet portion, of a screen jwithi'n the walls of said conical portion of the body of said 111111, the meshes or perforations of which extend'not only to a point belowthe axis of the mill but also to a point below the inletopening, and means within said millfor removing the material as fast as it passes through the screen, whereby an unrestricted free flow o-t'i he material through thesci-ea is" provided.

t grinding mill of the class described COIIIPI'lSlIlg'iIll inlet'op'ening, a conical outlet portion, a screen within the walls of said jconicalportion of the body of said mill, the

"HARRY W. HARDINGE. 

